my cousin told me if i was going to lap the quarter panels on my duster to try and lap it on the inside of the old quarter that way water will run off and can't fall behind...And he did go to college for body work and worked on alot of old cars.
If you were fixing the roof on your house, I would worry about which way things overlap. On a car , Using lead (outside) and seam sealer (inside)... I would say overlap it to obtain the best fit. :toothy7: